chore: remove tini binary (#1503)

## Rationale
Our repo should not contain any binaries.

## Detailed Changes
- Download tini instead of hard copy

## Test Plan
CI

Also I use command below to ensure no other binaries exists.
```
fd -t file --exclude target --exec file {} \; | grep -v ASCII | grep -v UTF-8
```

.gitignore

@@ -10,3 +10,4 @@ integration_tests/dist_query/output
 .tools
 bin
 coverage.txt
+tini

Dockerfile

@@ -46,7 +46,8 @@ RUN chmod +x /usr/bin/horaedb-server
 COPY ./docker/entrypoint.sh /entrypoint.sh
 COPY ./docs/minimal.toml /etc/horaedb/horaedb.toml
 
-COPY ./docker/tini /tini
+ARG TINI_VERSION=v0.19.0
+ADD https://github.com/krallin/tini/releases/download/${TINI_VERSION}/tini /tini
 RUN chmod +x /tini
 
 ARG USER=horae

horaemeta/Dockerfile

@@ -44,7 +44,8 @@ RUN chmod +x /usr/bin/horaemeta-server
 COPY ./docker/entrypoint.sh /entrypoint.sh
 COPY ./config/example-standalone.toml /etc/horaemeta/horaemeta.toml
 
-COPY ./docker/tini /tini
+ARG TINI_VERSION=v0.19.0
+ADD https://github.com/krallin/tini/releases/download/${TINI_VERSION}/tini /tini
 RUN chmod +x /tini
 
 ARG USER horae